Vascular injury plays an important role both in the pathogenesis and in the angioplasty treatment of atherosclerotic blood vessel disease. The knowledge on the precise molecular structure and function of a number of vascular growth factors is rapidly increasing, but how these molecules control the response to vascular injury in the complex environment of living tissue is poorly understood. The broad objective of this project is to understand the precise role of one representative growth factor in vivo in a well defined sequence of responses to vascular injury, using locally transfected cells as probes. Our hypothesis is that fibroblast growth factor 1 (FGF-1) is a necessary and essential controlling substance in the vascular wound healing process. Based on a large and continuously growing foundation of in vitro findings, we will intervene experimentally in vivo with this growth control mechanism in various directions (up- or down regulating, timing, local gradients) through somatic gene transfer of mutant variants of the growth factor or the respective receptors, and through interference with FGF-1 specific molecular post-translational pathways of cellular release and extracellular activation in response to the local redox milieu. Although not the major goal, but a beneficial additional effect could be the new knowledge that may improve in situ somatic gene transfer for therapeutic reasons. In Aim 1, we will improve our currently used vascular gene transfer to a level of efficacy where an actual dose-effect relationship can be established by determining how many cells of which type are transfected with the gene and how long they express it in the milieu of a standardized vascular balloon injury in rats and mice. In Aim 2, we will transfect cells at these vascular injury sites with a number of mutant genes which alter FGF-1, its receptor FGFR-1, and the c- src/cortactin part of the intracellular receptor signalling pathway with the intent to exaggerate or block the growth factor system at defined steps of a complicated cascade. In Aim 3, we will explore how the release and extracellular activation of the growth factor may be controlled by oxidation-reduction mechanisms that also play a role int he oxidation and atherogenicity of lipoproteins. We suggest that the data obtained from these studies be useful for the better understanding and potential clinical management of the large number of diseases that involve vascular injury, vascular cell hyperplasia and abnormal responses to regulatory stimuli, ranging from intimal thickening early in atherosclerosis to the healing of spontaneous fissures late in this disease, and the excessive response to revascularizing interventions known as restenosis. If successful, these data will have identified potential novel key intermediates for rationale drug design on a genetic basis as well as effective methods of local application and control.